Why is shortsightedness on the rise?
Short-sightedness is on the rise, especially in children.
The reasons are various and not what you might expect.
Originally short-sightedness (myopia) was thought to be genetic, but then scientists conducted studies on populations that initially had been nomads. They did not use their eyes to study (or for other near vision tasks).
For example, the Inuit led traditional lifestyles which were isolated, and researchers found the Inuit had a very low incidence of myopia. Only less than 1% was myopic.
However, after the Inuit population moved into the cities, up to half of the children developed myopia. Researchers concluded that this was too fast for it to be a genetic evolution, so they found it had to be due to something else.
Donald Mutti, an optometrist at Ohio State University Medical Center, published a paper called “Parental history of myopia, sports, and outdoor activities and future myopia” made some interesting findings.
He and his team examined children aged 8 to 11 years. He had 514 children, and 111 (21.6%) became myopic.
He looked at many factors (as can see from the title of his paper). He looked at:
- the number who had myopic parents or genetic factors,
- how many hours per week children engaged in activities such as sports and other outdoor activities, and
- the number of hours they spent reading per week.
The children who developed myopia were the ones who spent less time in the open air doing sports and outdoor activities than those who had spent their time indoors doing activities which involved near vision.
As a result, the researchers realised that the incidence of myopia was increasing because our customs are becoming much more sedentary, particularly in the childhood age group.
Children are spending much less time outside in the fresh air. They were doing fewer activities in which they required distance vision and more activities in which they needed near vision.
Children spend many more hours each day and each week in leisure pursuits which involve their near vision and with artificial light, from a lamp in the evening or the screen light from their laptop or computer.
These hours are not necessarily leisure hours as they also include their academic hours where they are studying at school or home doing their homework. These near-vision tasks force them to use their eyes in poor illumination and to focus on near objects such as their screen or their exercise book.